Generally, a download manager enables downloading of large files or multiples files in one session.Many web browsers, such as Internet Explorer 9, include a download manager.Stand-alone download managers also are available, including the Microsoft Download Manager.

if you do not have a download manager installed, and still want to download the file(s) you've chosen, please note:

You may not be able to download multiple files at the same time.In this case, you will have to download the files individually.(You would have the opportunity to download individual files on the "Thank you for downloading" page after completing your download.)

Files larger than 1 GB may take much longer to download and might not download correctly.

You might not be able to pause the active downloads or resume downloads that have failed.

The Microsoft Download Manager solves these potential problems.It gives you the ability to download multiple files at one time and download large files quickly and reliably.It also allows you to suspend active downloads and resume downloads that have failed.

The Windows Phone SDK Update for Windows Phone 7.8 adds two new emulator images to your existing Windows Phone SDK installation. This update supports both the Windows Phone SDK 7.1 and the Windows Phone SDK 8.0. Using this update, you can provide the Windows Phone 8 Start screen experience in your Windows Phone 7.5 apps. You can also test how your apps will run on Windows Phone 7.8 devices.

Ensure that you have the Windows Phone SDK 8.0 or Windows Phone SDK 7.1 installed.
Click the Download button for WPexpress78_update.exe file and then select the option to Run and follow the instructions that appear.
Note: If you have both the Windows Phone SDK 8.0 and Windows Phone SDK 7.1 installed on the same computer, both SDKs will be updated.